Complete reorganization of the Predis\Connection namespace.

* Renamed SingleConnectionInterface to NodeConnectionInterface since
  this name is better and makes even more sense in the context of
  cluster and replication scenarios.

* Moved specialized aggregate connections (the ones implementing both
  predis and redis cluster and master/slave replication) in a newly
  created Predis\Connection\Aggregate sub-namespace.

* Removed the "Connection" part from names of aggregate connection
  interfaces in the Predis\Connection\Aggregate sub-namespace.

* Changed "Composable" to "Composite" in the name of interfaces and
  classes that can use pluggable protocol processors.

tests/Predis/Protocol/ProtocolExceptionTest.php

@@ -14,7 +14,7 @@ namespace Predis\Protocol;
 require_once __DIR__.'/../CommunicationExceptionTest.php';
 
 use Predis\CommunicationExceptionTest;
-use Predis\Connection\SingleConnectionInterface;
+use Predis\Connection\NodeConnectionInterface;
 
 /**
  *
@@ -24,7 +24,7 @@ class ProtocolExceptionTest extends CommunicationExceptionTest
     /**
      * {@inheritdoc}
      */
-    protected function getException(SingleConnectionInterface $connection, $message, $code = 0, \Exception $inner = null)
+    protected function getException(NodeConnectionInterface $connection, $message, $code = 0, \Exception $inner = null)
     {
         return new ProtocolException($connection, $message, $code, $inner);
     }